Jake Paul and Zayn Malik's online shouting match -- via Gigi Hadid -- got started with what sounds like a hard snub to come get crazy with the YouTube broskis.
Sources close to Jake tell TMZ ... both he and Zayn were staying at the same hotel in Vegas over the weekend, and they were even on the same floor with rooms next to each other. We're told that after the fight, Jake was making his way back to his room when he spotted Zayn and co.